EP1 748 859 B1 describes what is known as a spade bit in which two main cutting edges are connected in the region of a center via a chisel edge. The main cutting edges lie in a common horizontal end face plane. The main cutting edges also extend in a straight line. In the area of the center and the chisel edge, a point thinning is made in a separate grinding step, the ground face thereby being formed extending outward in a radial direction to a cutting corner and forming a face land which is oriented at a rake angle. Blind holes having a flat bore base can be reliably produced with a spade bit of this sort.
EP 1 230 058 B1 describes a drill bit with main cutting edges onto each of which joins a flank, the flanks respectively having two sub-regions that transition into one another homogeneously and edgelessly. A method for grinding the drill bit is also described in which the flank is formed as a curved surface in one sub-region. In operation, the load on the drill bit is less due to this embodiment with a shoulderless surface profile.